Existing SAW devices have been used in a variety of fluid, physical and chemical sensors. Features of SAW sensors include an ability to operate without an external power-supply and an ability to be interrogated wirelessly. Wireless sensor communication systems involve multiple components including sensor, antenna and interconnections. These separate elements lead to added cost and complexity, fabrication difficulties and reliability issues.
Some Antenna-in-Package (AiP) devices are known as in “Novel Antenna-in-Package Design in LTCC for Single-Chip RF Transceivers”, Zhang, Y. P.; Sun, M.; Lin, W.; Antennas and Propagation, IEEE Transactions, Volume 56, Issue 7, July 2008, Pages 2079-2088 and Y. P. Zhang, “Integrated-Circuit-Pressed Ceramic-Package Antenna”, Microwave Opt. Technol. Lett. 42: 143-147, 2004. However, these are designs for antennas for radio communications requiring maximum range, far-field pattern uniformity and specific polarization. They are implemented in radio transceivers for communication applications such as those employing the IEEE standard 802.11a. These antennas transmit at 5.775 GHz and are matched to a 50 ohm source. For these applications, global optimizations are necessary resulting in particular design parameters. Achieving these objectives results in expensive, complex devices and does not address the need for close-coupled, passive-wireless sensors with little or no radiated power and similar applications.
Particular sensor devices have been disclosed comprising inductively coupled interrogation and sensor components such as the Liu Passive Hybrid LC/SAW/BAW Wireless Sensor patent application US 2007/0051176. The Liu application discusses sensors coupled to interrogation circuits by wires, radio transmission, and inductive coupling. It does not identify solutions with sensor packages that include integrated coupling and sensing components.
Capacitive coupling of AWD components internal to their packages have been described as in “Fast SAW Based Sensor System for Real-Time Analysis of Volatile Anesthetic Agents”, Barie, N.; Voigt, A.; Rapp, M.; Marcoll, J., Sensors, 2007 IEEE, 28-31 Oct. 2007, pages: 958-961.
What is needed, therefore, are techniques for cost-effective, flexible, integrated-package wireless acoustic wave devices (AWDs) for near-field coupling to associated instrumentation.